Telephone-transmitter.



i PATENTED DEC. 4, 1906.

P. W.'FAHRENPELD.

TELEPHONE TRANSMITTER.

APPLIOATION FILED AI IG 31,1905.

31 wanten',

"UNITED STATES PATENT OFFICE.

FRED W. FAHRENFELD, OF ROCHESTER. NEW YORK, ASSIGNOR TO THE SIMPLEX TELEPHONE EQUIPMENT COMPANY,

YORK, A CORPORATION OF NEW YORK.

v TELEPHONE-TRANSMITTER.

. Specification ofLetters Patent.

Patented Dec. 4, 1906.

Application fina August s1, i905. Serin No, 276,495.

1o vof the specification, and to the reference-numerals marked thereon.

My present invention relates to telephony; and it has for its object to provide a transmitter for telephone instruments that shall be simple in construction and com rise few parts capable of withstanding roug usage, and which are designed particularly. to form a 'compact articleof small size, althou h equally well adapted to be employed in maing large zo transmitters.

vMy invention has for its further object to .3oA fully describe-d, the novel features being pointed out in the claims at the end of the speciiica-V tion.

In the drawingsl Figure 1 is a plan view of the transmitter in accordance with my invention. Fig. 2 is an enlarged cross-sectional view thereof, showing diagrammatically a telephone-cirf cuit in which it is adapted to be arranged.

Fig. 3 is a detail plan view of the vibratory diaphragm. Fig. 4 is a similar view of the bridge su porting the back electrode. Fig. 5 is an en arged plan view of oneof the electrodes. Fig.. '6 is a cross-sectional view thereof.

Similar reference-numerals in the several figures indicatesimilar parts.

A transmitterl constructed in accordance with my invention embodies a metallic cup- I Isllilfied cylindrical case having the bottom 1 5 0 8. a

the side wall 2, which-is covered on its cuter surface with insulation 3 which may be applied in the form of an enamel of rubber or othersuitable material. The' front for telephones constructed and back electrode-plates (indicated by 4 and 5, respectively) are arranged one upon a vibratory diaphragm 6 and the other upon a stationary bridge 7, comprising a cylindr cal metallic plate provided with perforati ns 8 and adapted to be seated on a shoulder 9 on a ring formed of gutta-percha, fiber, .or other insulating material, (indicated by 10.)

- This ring is formed of such a diameter that it may be pressed into the cu -shaped casing, and a bridge 7 is also made o such a size that when pressed against the shoulder 9 these' parts will be securely positioned. On the inner side of the bottom 1 is a small screw or bindin -post 15, and on the proximate side of the l) are connected the circuit-Wires 15a andla', respectively, which when the parts are assembled extend outwardly throu h re istering apertures in the ring 10 and t e wa l 2 of the casing; `The a erture in theside of the casing is protected y an insulating-bushin the apertures 8 to permit the escape of air from the casing, thus preventing the forming .of anair-cushion to interfere with the operation of the diaphragm. The diaphragm 7 comprises a thin metallic disk of a diameter equal to that of the casing, andr as it rests upon the edges ofthe sidewalls 2 1t is in electrical connection therewith. The ca -piece 18 secures the dia hragm in lace an its inner side is recessed? and provi ed with a shoul der 19, which engages the face of the dia'- phra m at its outer edge, and it is also provide with a rim 20, ada ted to embrace the eri hery vof the side wa ls 2 ofthe casing to ol the parts in operative position, although other fastening devices may be employed, if desired. The outer face of the ca 18 is convex, and at the center itis provide with a series of perforations '21, through which air vibrations may effect the opera; tion of the diaphragm 6; V

The arrangement and construction of the foregoing parts enables the transmitter to be made small'in size; but as devices of this owing to the small area of the cooperating 'parts-serving to make and break'the electric circuit I employ plates which, although small in diameter, possess relatively large contactsurfaces. To accomplish this object, I pro- OF ROCHESTER, NElV ridge 7 is a similar post `16, to which "17. and forms a vent which coperates Wit i character are usually inefficient in operation videthe plates With numerous projections ving intersecting slots in the face of the plate,

bratory diaphragm 6 and to the ter in place as Will be understood. I n practice these plates are permanently secured vto the vi. y bridge-piece 7 by rivets 22, with the pointedprojections on one plate directly above andy in proximity to the points of the projections on the othei plate. The bridge-'piece 7 located rela- 'tively to the diaphragm, so thatthe o posingprojections on vtact, andthe the plates .areout' o con# rial, such4 as granular carbon,f'generally employed for this,v purpose, and to', h0`ld the ,lat

rial, which rests on 4the bridge and extends into proximity With the diaphragm. To further increase the conductivity Aof the plates, their surfaces are plated with gold or similar non-corrosive metal.

A transmitter I embodying my invention consists of few partsv Which are.simple 'in construction and may be readily assembled.

/ carbon or other granular conductive material from becoming packed between them.

I claim as my invention- 1. In a transmitter, the combination with a `cup-shaped casing of conductive material provided With an aperture and comprising a back and an annular rim, a covering of insulating material applied to the exterior oi the casing, and an insulated bridge in the latter, of means on the bridge and on the interior of the casing for securing the conductors of a telephone-circuit to said parts, a diaphragm extending over the riin of the casing, a cap-piece of insulat-V ing material engaging the diaphragm and fitting over theexterior of the casing, electrode-plates on the bridge and diaphragm and conductive material between said plates.

2. In a transmitter, the combination with.

- a cup-shaped metallic casing provided with an aperture and comprising a back' and an an'- nular rim, a perforated bridge fitted within the rim' and closing the casing, of a diaphragm also closing the casing andv in electrical connection therewith and arranged over the bridge, electrode-plates on the bridge and diaphragm and conductive mateand a vibratory telephone-circuit will be com-A pleted through the loose conductive rriate-v `said shoulder, of a vibratory diap 4cured at itsedges to vthe edges of the side c L betweenv the plate's I -employ a' ring 23, of felt or other non-conductive mate- .a casing' having an a casing having an the bridge and supported onrial between said plates, a cap-piece itting the rim and securing the diaphragm thereon,

and means on the bridge and casing for securing. the'conductors of a telephone-circuit to said parts Within the casing.

3. Ina transmitter, the combination a metallic casing, a metallic. bridge-piece supported therein'and insulated therefrom diapliragmclosing the casing and connected thereto, of electrode-plates mounted in opposition to each other .on the diaphragm an'd bridge, said plates and Aresting on the bridge Without engaging the diaphragm and granularcon- `ductive material between the plates.

4. `In a transmitter, the combination With a casing having a side Wall, a ring of insulat- -ing material located Within said Wall having.

orted on agm sea shoulder and a bridge-piece sup walls, electrode-plates secured to the bridgewith' a ring surrounding piece and diaphragm and granularI conf ductive material located'between the plates. 5. In a transmitter, the combination With annular side Wall, a ring of insulating material fitted therein having an annular shoulder and a bridge-piece sup- `ported thereon, of a vibratory diaphragm resting on the edges of the Walls of the .cas- ',ing, a cap iitting over 1t and engaging the outer side of said. Wall, and cooperating electrode-plates on the diaphragm and bridge.

6. In a transmitter, the combination with.

annularsid e Wall, a ring oi' insulating material fitted therein having an annular shoulder and a bridge-piece sup'-,

ported thereon, of a vibratory diaphragm IOO resting on the edges ofthe Walls of the casing Y.

and a perforated cap covering the diaphragm and provided with a shoulder engaging the edge oi the diaphragm, a rim on the cap' eny`g'a, r,ingthe outer side of the Wall of the casing and cooperating electrode-plates on the diaphragm and bridge.

7. In a transmitter, the combination with a metallic casing having alaterally-extending side Wall provided with 4a perforation and adapted to be connected to one side of a telephone-circuit, an insulating-ring in the cas-l ing provid ed with an aperture registering W ith the perforation in the casing and aperforated IIO metallic bridge-piece adapted to be connected to the other side of a telephone-circuit, of a vibratory metallic diaphragm engaging the side wall of the casing, a cap resting on the diaphragm and having a rim engaging the IZO exterior of said wall and .conductive material located between the diaphragm and bridge. nnen W. raimnNrELnl W'itnesses: i l

G. WrLLARD Rien, FREDERICK F. CHURCH. 

